Sander

Abstract

A sander can include a housing, an indicator coupled to the housing, and a motor assembly in the housing. The motor assembly can include an output member. A platen can be driven by the output member. A DC generator can be driven by the output member. The DC generator can generate an output signal with a voltage that is related to a rotational speed of the motor. A controller can operate the visual indicator based on the voltage of the output signal. According to additional features, the DC generator can provide electrical power to operate the indicator. An electric power input can be electrically coupled to the motor. The visual indicator can be electrically isolated from the electric power input.

1. A sander comprising:
 a housing; 
 an indicator coupled to the housing; 
 a motor assembly in the housing, the motor assembly including an output member; 
 a platen coupled to the housing and driven by the output member; 
 a DC generator driven by the output member, the DC generator generating an output signal with a voltage that is related to a rotational speed of the motor; and 
 a controller that operates the indicator based on the voltage of the output signal. 
 
   
   
     2. The sander of  claim 1  wherein the DC generator provides electrical power to operate the indicator. 
   
   
     3. The sander of  claim 1 , further comprising an electric power input electrically coupled to the motor, wherein the indicator is electrically isolated from the electric power input. 
   
   
     4. The sander of  claim 1  wherein the controller is configured to communicate with the indicator to display a first output based on the output signal satisfying a first criteria, and a second output based on the output signal satisfying a second criteria. 
   
   
     5. The sander of  claim 4  wherein the indicator comprises at least a first and a second light source, wherein the first output includes illumination of the first light source and the second output includes illumination of the second light source. 
   
   
     6. A power tool comprising:
 a housing with a platen located on a lower portion of the housing for working a surface; 
 a motor located in the housing, the motor having a rotary output shaft that drives the platen; 
 a DC generator located in the housing, the output shaft powering the DC generator; and 
 a controller and an indicator; 
 wherein the DC generator outputs a signal to the controller to indicate the speed of the output member which corresponds to the pressure applied to the platen, the controller transmitting a signal to the indicator. 
 
   
   
     7. The power tool of  claim 6  wherein the DC generator outputs a voltage to the controller. 
   
   
     8. The power tool of  claim 6  wherein the DC generator powers one of the controller or the indicator. 
   
   
     9. The power tool of  claim 6  wherein the output shaft includes a first gear and the DC generator includes a second gear, the first gear meshing with the second gear to power the DC generator. 
   
   
     10. The power tool of  claim 6  wherein the controller is programmed with predetermined speed ranges corresponding to acceptable pressures and excessive pressures being applied to the platen, the controller being adapted to send the corresponding signal to the indicator. 
   
   
     11. The power tool of  claim 10  wherein the indicator comprises at least two lights, one light being green to indicate the acceptable pressure and the second light be red to indicate the excessive pressure. 
   
   
     12. The power tool of  claim 10  wherein the controller includes a calibration mode that allows it to alter the predetermined ranges, the controller determining the new ranges by allowing the output member to rotate freely and computing new acceptable and excessive ranges therefrom. 
   
   
     13. The power tool of  claim 10  wherein the power tool is a palm sized sander, the housing having a top portion sized to fit within the palm of a user's hand, and a forward portion of the top portion having the indicator.